Include `dflcn-win32` library binary

Currently, the Windows API is not fully covered. We could rely on this compatible layer to do dynamic loading of shared libraries. We already have dflcn.adept (https://github.com/AdeptLanguage/AdeptImport/blob/master/unix/dlfcn.adept) and it could be reused with dflcn-win32.

https://github.com/dlfcn-win32/dlfcn-win32

[IsaacShelton]

That would be nice to have yes